The Design Of A Dual-phase Dc Motor Drive Chip With Current Sampling Function

With the continuous development of semiconductor technology and Power electronics technology,Smart Power Integrated Circuit（SPIC）is gradually becoming more intelligent,power-oriented and systematized,which promotes the automation process of industrial production and daily life.As an important part of the motor drive chip,it has a broad development prospect in advocating green environmental protection,energy saving and emission reduction today.Based on Hynix 0.18μm BCD process,a dual-phase DC motor driver chip with current sampling function is designed in this paper.The operating voltage of the chip is 4.5～37V,the applicable temperature range is-40～150℃,with enable/write（EN/IN）,Pulse Width Modulation（PWM）,independent half-bridge three working modes,Two current regulation modes,fixed turn-off time current chopper and periodic current chopper,are designed.Based on voltage clamping sampling tube MOSFET current sampling structure design is a kind of integrated inside the chip of current sampling circuit,by putting forward a kind of special current mirror architecture,multiple image tube series,the sampling tube parallel connection,increases the image tube length and sampling tube gate width of the gate in whole,in satisfies the premise of map matching can effectively restrain the channel length modulation effect,Improve the accuracy of current mirror.On the other hand,a high-performance folded common Source common gate（Cascode）error amplifier is used to clamp the current mirror architecture,and a modification module is designed in the error amplifier to reduce misalignment,which can obtain good accuracy at a large sampling ratio.In order to achieve the function of current regulation,a sampling current processing circuit is designed.The sampled current is input to Cascode current mirror,and the current obtained by Cascode current mirror is converted into voltage through the small resistance outside the chip and input to Anolog Ditital Convertor（ADC）.At the same time,the current is input into the comparator circuit to get the current chopper signal,so as to realize the current regulation function of the chip.In order to prevent the ADC module from being damaged by the excessive current sampled,an external ADC protection circuit is designed.In order to further improve the reliability of the chip,over current,over temperature and over voltage protection circuits are added to ensure the safety of the chip and motor load under extreme circumstances.This paper first analyzes the working principle of H bridge,and then introduces in detail the three control modes and two current regulation modes in this design,and based on this,carries on the design of high-precision current sampling circuit and sampling circuit processing circuit.The submodules supporting current regulation function in the chip are introduced in detail,including prevoltage regulator circuit,bandgap reference circuit,reference current source circuit and low voltage difference linear voltage regulator circuit.The control signal processing circuit module includes processing circuit of dormant signal,IN1/IN2,PMODE and IMODE.Cadence spectre is used to simulate and verify each sub-module and the whole circuit.Simulation results show that the functions of the three control modes and the two current regulation modes are correct,the static current and dormant current are 2.47 m A and 12.6μA respectively,the current sampling error is 0.81%,the current detection delay is 860 ns,the fixed shutdown time is 22μs,and the propagation delay from input to output is 550 ns.Finally,based on the layout reliability design and matching principle,some important sub-modules and the overall layout design are given.The overall layout area is 1.94 mm×1.94 mm.